The present disclosure relates to an organic electroluminescence (EL) element and a method for production thereof.
Display apparatuses based on an organic EL element are prevailing nowadays. The organic EL element is characterized by good visibility owing to its self luminescence and high impact resistance inherent in solid-state device.
Being a current-driven element, the organic EL element is composed of paired electrodes and functional laminated layers interposed between them. The electrodes are a pixel electrode and a counter electrode. The functional layers include an organic luminescence layer capable of electroluminescence by carrier recombination and a hole injection layer or an electron injection layer to promote carrier injection from the anode and the cathode.
Moreover, the organic EL element additionally has an interlayer insulation layer and a layer called bank. The former is intended to planarize the substrate surface on which are formed thin film transistors (TFTs). It helps the organic luminescent layer to be formed uniform in thickness. The bank defines the area for luminescence (see Japanese Patent Laid-open No. 2005-227519, for example).
In addition, the organic EL element may have a metal thin film coated with a transparent conductive layer formed from a metal oxide such as indium tin oxide (ITO) and indium zinc oxide (IZO) (see Japanese Patent Laid-open No. 2011-9790, for example).